A Climate That Came and Went: Limit Cycles and the Changing Weather of Ancient Mars
The paper proposes that early Mars may have undergone episodic limit cycles, long cold periods interrupted by short warm intervals triggered by volcanic CO₂ buildup and enhanced greenhouse gases. Using a simplified climate model, Haqq-Misra shows that these warming spikes align with the timing of valley networks and delta formation. The study suggests Mars’ wet features may reflect transient, not sustained, warm climates driven by cyclic atmospheric processes.
Could Mars Have Melted Ice Recently?
The study investigates whether liquid water could have formed Mars’ young gullies in the past 4 million years. Using advanced climate models, the authors find that surface frost cannot melt because sublimation cools it too strongly, and subsurface ice stays too deep and cold for melting. Even when ice is suddenly exposed, melting requires unrealistic conditions and produces too little water. The results suggest that most gullies likely formed through dry CO₂-driven processes rather than flowing water.